I. Field
The following description relates generally to wireless communications, and, amongst other things, to coordinating communications within an electronic device communicating utilizing two or more separate communication protocols.
II. Background
Many electronic devices utilize multiple communication protocols. For example, a laptop may use a wireless personal area network (WPAN) (e.g., Bluetooth) to connect the laptop to a wireless mouse, wireless keyboard and the like. In addition, the laptop may include an Institute for Electrical and Electronic Engineers (IEEE) 802.11b or 802.11g device to allow the laptop to communicate with a wireless local area network (WLAN). WLANs have become increasingly popular. It is not unusual for people to set up a WLAN in their homes. In addition, WLANs have become widely available at coffee shops, libraries and other public and private locations. Mobile phones have also begun utilizing multiple communication protocols such as Cellular, WLAN and Bluetooth. Mobile phones and personal digital assistants (PDAs) have become multifunctional devices providing email, Internet access as well as traditional cellular communication. Mobile phones may also utilize a WPAN to communicate with an earpiece or other device.
Certain wireless communication protocols overlap each other in terms of the frequency ranges in which they operate. For example, Bluetooth and IEEE 802.11b/g devices share the same spectrum. Bluetooth is a standard communication protocol that provides for data transfer within a range of approximately ten meters. Both Bluetooth and IEEE 802.11b/g devices operate in Industrial, Scientific and Medical (ISM) band between 2.4 GHz and 2.4835 GHz. Bluetooth device transmissions use approximately 1 MHz bandwidth and hop over 79 MHz of the ISM band. Bluetooth devices utilize a frequency hopping spread spectrum technique that changes signal approximately 1600 times per second. IEEE 802.11b/g devices operate at a fixed frequency, one of three non-overlapping 22 MHz channels, or 16.7 Mhz if the device is using orthogonal frequency division multiplexing (OFDM). Therefore, there is approximately a 28% chance (22 channels utilized by IEEE 802.11b/g device/79 total channels) that a Bluetooth transmission will be transmitted in one of the channels being utilized by an IEEE 802.11b/g device and interfere with the WLAN transmission.
In order to mitigate potential for collisions, Bluetooth Version 1.2 specifies an Adaptive Frequency Hopping (AFH) scheme. During AFH, the Bluetooth transmissions avoid channels of IEEE 802.11b/g and hop on remaining spectrum available for Bluetooth transmissions. However, relatively few devices incorporate the AFH scheme at this time. Moreover, when Bluetooth device transmitters and IEEE 802.11b/g device transmitters are co-located within a wireless communication device, e.g. handset, the signal power from one device may interfere with the other device even when the devices are transmitting and receiving at different frequencies.
When the Bluetooth and IEEE 802.11b/g device transceivers are in close proximity, signals being transmitted from the first device can saturate the low noise amplifier (LNA) of the second communication device, causing the second device's receiver to be desensitized. The transmit power of IEEE 802.11b/g devices is approximately 17 dBm. However, these devices operate over a range of up to 30 meters. Therefore, the power at the receiver is quite small. Typically, Bluetooth uses 10 to 15 dB lower power than an IEEE 802.11b/g device, but the range of the Bluetooth device is very short and therefore the power at the receiver is greater. Accordingly, if an IEEE 802.11b/g device is receiving a packet at the same time the Bluetooth device is transmitting, the transmit energy of the Bluetooth device will spill into the transceiver of the IEEE 802.11b/g device and desensitize the receiver. The desensitization of a receiver may cause loss of signal and failure in communication. Co-location of the communication devices may include utilizing the same antenna, location on the same circuit board or coupled circuit boards, location on the same chip or coupled chip sets and combinations thereof.
Co-location of a Bluetooth device and an IEEE 802.11b/g device may result in interruption of signal and loss of data. Therefore, there exists a need to prevent communication failures when a Bluetooth device is co-located with an IEEE 802.11b/g device.